The Museum of HP Calculators

HP Forum Archive 19

 HP 35s Gnome SortMessage #1 Posted by Elliott W Jackson on 13 Feb 2009, 10:52 p.m. Well, I decided to try my hand at something a bit more ambitious than my last little project (linear interpolation, released here to stunning, and yet oddly silent fanfair. I'm sure everyone was just over-awed and unable to comment. Yeah, that's the ticket). I thought maybe a simple sort routine would be a good project. I did a search, and found a nice page on Wiki with all sorts of algorimthms, with a nice summary of speed, complexity, storage requirements, etc. I selected the Gnome Sort, since it seemed to be the smallest, simplest. Pseudo-code follows: ```void gnomesort(int n, int ar[]) { int i = 0; while (i < n) { if (i == 0 || ar[i-1] <= ar[i]) i++; else { int tmp = ar[i]; ar[i] = ar[i-1]; ar[--i] = tmp; } } } ``` Couldn't be much simpler, right? Well, as I set about transforming this simple, benign bit of C code into HP-calc-ese, with all it's GTO and lack of labelling capability glory, I quickly re-learned the lesson of why I haven't used a "goto" command in over two decades. Goto sucks. I REALLY struggled to transform the if-then-else logic into goto-ese. It was made more complex because the operand of the if() statement is a compound statement with OR logic. I'm quite confident someone could turn that into something better than I came up with, I ended up kludging it together with several GTO statements and Flag 0. For better or worse, here is the program. It is called assuming bbb.eee is in the X-stack, and will then gnome-Sort the contents of memory registers 'bbb' to 'eee', in ascending order. Note that it will not sort complex or vector contents. Memory registers used: I, J, Y, Z Flags used: 0 ```S001 LBL S S002 INTG S003 STO I S004 STO Y first register to be sorted S005 LASTX S006 FP S007 1000 S008 * S009 STO Z last register to be sorted S010 CF 0 start of while (I < n) loop S011 RCL Y first register S012 RCL I current register S013 x == y? if(i==0) S014 SF 0 S015 1 S016 - S017 STO J S018 RCL (I) ar[i] S019 RCL (J) ar[i-1] S020 x <= y? if(ar[i-1] <= ar[i]) S021 SF 0 S022 FS? 0 if ( (i==0) || (ar[i-1] <= ar[i]) ) S023 GTO S030 S024 STO (I) ar[i] = ar[i-1] S025 RDN S026 STO (J) ar[i-1] = ar[i] S027 1 S028 STO- I i--; S029 GTO S032 S030 1 S031 STO+ I i++; S032 RCL Z S033 RCL I S034 X <= Y? while(i

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